I solved the problem. The problem was not that the image was deleted, but that it was automatically converted to WebP format by another plugin. When I converted the images from the website back to JPG format, the preview section started working again. I read in many comments that WebP support is coming for the paid version. I wonder when it will come? If so, I would like to buy it as soon as possible!
Hi Kuba, thank you for answering. I deleted watermark and added new one but it keeps the preview image info. I will check post meta table.
